Diaphragm pump

ABSTRACT

A diaphragm pump having a housing, an operating rod projecting within the housing and mounted therein for reciprocating translational movement, a rotatable camshaft mounted in the housing for reciprocating the operating rod, an electric motor for driving the camshaft and strain wave speed reducing gearing interposed between the motor and camshaft for rotating the camshaft at slow speed from the relatively high speed motor. Such gearing includes an external ring gear having internal teeth fixed to the housing, a deformable internal strain gear having external teeth in cooperative engagement with the ring gear, the strain gear being drivingly connected to the camshaft, and a strain inducer mounted internally of the strain gear in cooperative engagement therewith, the strain inducer being drivingly connected to the motor. The pump also includes a yoke fixed to the operating rod within the housing, cam and follower means interposed between the camshaft and yoke for driving the yoke in one direction, spring means interposed between the yoke and the housing for moving the yoke in an opposite direction and adjustable stop means for limiting movement of the yoke in the opposite direction to establish an adjustably predetermined stroke of the pump.

United States Patent 11 1 [111 3,801,232

Kilayko Apr. 2, 1974 DIAPHRAGM PUMP 57 ABSTRACT [75] Inventor: Enrique Locsin Kilayko, A diaphragm pump having a housing, an operating rod Auburndale, Mass. projecting within the housing and mounted therein for [73] Assignee: Precision Control Products recipgoating zq fi f fi a roiatable Corporation, waltham, Mass. cams a t mounte In t e ousmg or reciprocating the operating rod, an electric motor for driving the cam- [22] Filed: Aug. 15, 1972 shaft and strain wave speed reducing gearing interposed between the motor and camshaft for rotating [211' Appl' 2808l6 the camshaft at slow speed from the relatively high speed motor. Such gearing includes an external ring [52] US. Cl. 417/413, 92/13.8 gear having internal teeth fixed to the housing, a de- [51] Int. Cl... F04b 43/00, F04b 45/00, F15b 15/24 formable internal strain gear having external teeth in [58] Field of Search 417/413, 470, 471; cooperative engagement with the ring gear, the strain 92/13.8 gear being drivingly connected to the camshaft, and a strain inducer mounted internally of the strain gear in [56] References Cited cooperative engagement therewith, the strain inducer UNITED STATES PATENTS being drivingly connected to the motor. The pump 2,718,343 9/1955 Brown 417 413 also inclfdes a yoke fixed) the operatlng rod within 2,906,143 9/1959 Musscr 74/640 the housing, cam and follower means interposed be- 2359960 10/1944 Anderson 417/471 tween the camshaft and yoke for driving the yoke in 3,157,221 11/1964 Keil 417/214 one direction, spring means interposed between the 1,905,284 4/1933 Heitger 417/471 yoke and the housing for moving the yoke in an oppo- 2,9l2,935 11/1959 W at 2/ site direction and adjustable stop means for limiting 3,175,473 3965 movement of the yoke in the opposite direction to es- Boteler et al. 92/13.8

Primary ExaminerWilliam L. Freeh Assistant ExaminerLouis T. Casaregola tablish an adjustably predetermined stroke of the pump.

1 Claim, 9 Drawing Figures "ATENTEUAPR 2 99M SHEET 1 DP 3 [FIGQ 1 PATENTED W 21974 SHEET 2 [IF 3 FIG.

PATENTEDAPR 2 I974 SHZET 3 OF 3 IFIG. 4 32 DIAPHRAGM PUMP This invention relates to diaphragm pumps for chemical metering and the like and more particularly to a novel drive mechanism for such pumps.

It is a major object of the present invention to provide a much improved diaphragm pump having smaller and lighter operating mechanisms than those heretofore in use.

Accordingly, the present invention provides, in a diaphragm pump having a housing, an operating rod projecting within the housing and mounted therein for reciprocating translational movement, a rotatable chamshaft mounted in the housing for reciprocating the operating rod and an electric motor for driving the camshaft, strain wave speed reducing gearing interposed between the motor and camshaft for rotating the camshaft at slow speed from the relatively high speed motor. Such gearing includes an external ring gear having internal teeth fixed to the housing, a deformable internal strain gear having external teeth in cooperative engagement with the ring gear, the strain gear being drivingly connected to the camshaft, and a strain inducer mounted internally of the strain gear in cooperative engagement therewith, the strain inducer being drivingly connected to the motor. The pump of the invention may also include a yoke fixed to the operating rod within the housing, said yoke having a central opening with its axis perpendicular to the operating rod with the camshaft extending through it, cam and follower means interposed between the camshaft and yoke for driving the yoke in one direction, spring means interposed between the yoke and the housing for moving the yoke in an opposite direction and adjustable stop means for limiting movement of the yoke in the opposite direction to establish an adjustably predetermined stroke of the pump.

For the purpose of more fully explaining still further objects and features of the invention, reference is now made to the following detailed description of a preferred embodiment thereof, together with the accompanying drawings, wherein:

FIG. 1 is an exploded isometric view, partly in section, of a diaphragm pump according to the invention;

FIGS. 2, 3 and 4 are, respectively, top, side and end sectional views of the pump of FIG. 1;

FIG. 5 is a cross-sectional view of a portion of the pump of FIGS. 1 through 4, taken on line 55 of FIG. 4; and

passageway 22 to an arrangement of one way valves (not shown) in a valve housing 24 to accomplish the pumping function in a well-known manner.

According to the present invention, a novel' drive mechanism is provided for reciprocating diaphragm operating rod 14 from a relatively high speed electric driving motor 30. In general, such mechanism includes a yoke 32, having a central opening 34, fixed to operating rod 14 within housing 12, a camshaft 40 mounted in said housing and extending through said yoke central opening, cam and follower means interposed between camshaft 40 and yoke 32 and strain wave speed reducing gearing, generally designated 60, interposed between motor and camshaft 40 for rotating said camshaft at slow speed.

More specifically, yoke 32 is generally planar and is rigidly mounted on the end of operating rod 14 generally parallel to the axis thereof within housing 12. It .is provided on the same side as operating rod 14 with upper and lower slide rods 36 slidably mounted therein, which rods bear against the wall of housing 12. Compression springs 38 are interposed between the remote ends of slide rods 36 in contact with housing 12 and yoke 32, normally to urge yoke 32 in a direction away from the wall of housing 12 upon which said rods bear. On its opposite side from operating rod 14, yoke 32 is provided with an adjustable stop mechanism for limiting movement of yoke 32 in the direction in which it is urged by springs 38. To this end, a stop mechanism slide rod 50 is centrally mounted on yoke 32, said rod being slidably received within a bore 52 on screw threaded adjusting member 54 which is threadably mounted in housing 12 and has its end within said housing adapted for contact with yoke 32. A knob 56 is provided on the end of member 54 outside of the housing for adjusting its axial position to establish an adjustably predeterminedstroke of diaphragm operating rod 14.

cam element 42 which contacts a circular cam follower FIGS. 6 through 9 are cross-sectional detail views showing successive steps in the operation of the portion of FIG. 5.

In the drawings is shown a diaphragm pump of the type having a housing 12 with a diaphragm operating rod 14 projecting within said housing and mounted therein for reciprocating translational movement. On its outer free end, operating rod 14 carries a flexible diaphragm 16 which is the operating element of a diaphragm pump, such as is shown in US. Pat. No. 2,741,187, for example. Thus, housing 12 has a circular boss 13 on one of its outer walls to which is secured the outer margin of diaphragm 16 by clamping it between said boss and the rim of a cup shaped pump base member 18, forming an enclosed sealed pumping compartment 20 of which diaphragm 16 is a reciprocating wall. The pumping compartment 20 is connected through 44 rotatably mounted on yoke 32 on the same side as operating rod 14 with its operating surface exposed within yoke central opening 34.

Camshaft 40 itself is driven at slow speed from motor 30 through strain wave speed reducing gearing 60, such gearing being disclosed in US. Pat. No. 2,906,]43 for example. In the preferred embodiment of the diaphragm pump herein disclosed such gearing 60 has a ratio of 48:! and includes an external ring gear 61 having axially extending internal teeth 62 fixed to housing 12, a deformable internal strain gear 64 having axially extending external teeth 65, at the same diametral pitch but of a slightly smaller pitch diameter, in number two less than those of ring gear 61, in cooperative engagement with the teeth 62 of ring gear 61 and a strain inducer mounted internally of strain gear 64 in cooperative engagement therewith. The difference in pitch diameter is caused by the fact that the number of teeth in this case on the strain gear is less than the number of teeth on the ring gear. The difference in the number of teeth between the two gears, or the tooth differential, is equal to or a multiple of the number of places at which the strain gear is deflected to cause tooth en gagement with the ring gear. This differential is desirably two, using a strain inducer having an elliptical contour with two lobes. The strain gear is made of a material which is elastic under the conditions of operation, and in the case of a steel strain gear, is made of relatively thin cross section so that it can be deflected easily in a radial direction. The strain inducer includes, mounted on'the shaft 31 of motor 30, an elliptical strain inducer member 70 having on its outer surface a ball bearing race 72 carrying bearing balls 74 which rotatably support the deformable strain gear 64. The

' strain gear by approximately the same amount. When the strain inducer is inserted into a position inside the strain gear, it causes the strain gear to be distorted into elliptical form, with the distance from the gear axis to the pitch-line of the teeth at the major axis equal to the pitch diameter of the ring gear. At the major axis the pitch circles of the two gears are coincident. At the minor axis the distance of the pitch line of the strain gear teeth from the gear axis is less than the pitch diameter of the ring gear, and if a full tooth height is used, -the teeth will just clear one another. At intermediate points, the teeth will have varying degrees of engage- 'ment. This condition prevails where the tooth differential is equal to the number of lobes on the strain inducer which in this case is two. FIGS. 5 through 9 are illustrative of the above.

In operation, motor shaft 31 rotates elliptical strain inducer 70 at a speed "of 3450 r.p.m., which in turn drives strain gear 64 within fixed ring gear at a speed i of 72 r.p.m. to rotate camshaft 40. The rotation of eccentric cam element 42 with camshaft 40 moves yoke 32 in opposition to springs 38 to provide the forward an operating rod projecting within said housing and mounted therein for reciprocating translational movement a yoke fixed to said operating rod within said housing, said yoke having a central opening with its axis perpendicular to said operating rod a camshaft mounted in said housing and extending through said yoke central opening cam and follower means interposed between said camshaft and said yoke for driving said yoke in one direction at least one spring loaded plunger mounted on said yoke for moving said yoke in an opposite direction between said yoke and said housing adjustable stop means for limiting movement of said yoke in said opposite direction to establish an adjustably predetermined stroke of said operating rod said adjustable stop means including screw threaded means threadably mounted in said housing and having an end within said housing forcontacting saidyoke an electric motor for driving said camshaft, and

strain wave speed reducing gearing interposed between said motor and said camshaft for rotating said camshaft at slow speed, including an external ring gear having internal teeth fixed to said housing a deformable internal strain gear having external teeth in cooperative engagement with said ring gear, said strain gear being drivingly connected to said camshaft and a strain inducer mounted internally of said strain gear in cooperative engagement therewith, saidstrain inducer being drivingly connected to said motor. 

1. A diaphragm pump comprising a housing an operating rod projecting within said housing and mounted therein for reciprocating translational movement a yoke fixed to said operating rod within said housing, said yoke having a central opening with its axis perpendicular to said operating rod a camshaft mounted in said housing and extending through said yoke central opening cam and follower means interposed between said camshaft and said yoke for driving said yoke in one direction at least one spring loaded plunger mounted on said yoke for moving said yoke in an opposite direction between said yoke and said housing adjustable stop means for limiting movement of said yoke in said opposite direction to establish an adjustably predetermined stroke of said operating rod said adjustable stop means including screw threaded means threAdably mounted in said housing and having an end within said housing for contacting said yoke an electric motor for driving said camshaft, and strain wave speed reducing gearing interposed between said motor and said camshaft for rotating said camshaft at slow speed, including an external ring gear having internal teeth fixed to said housing a deformable internal strain gear having external teeth in cooperative engagement with said ring gear, said strain gear being drivingly connected to said camshaft and a strain inducer mounted internally of said strain gear in cooperative engagement therewith, said strain inducer being drivingly connected to said motor. 